The article mentions they used Auth0 and Cognito. I spent quite a bit of time researching Cognito (https://github.com/baus/cognito-strap), but I never figured out how to recognize which user is logged in when using federated identities. I found the docs to be misleading or wrong in many cases.

I'm curious if anyone is actually using Cognito in production. It feels like an alpha product to me.